This is a randomized, double-blind trial of 2,3 dimercaptosuccinic acid (Chemet) on children aged 2-1/2 to 5 years with blood lead levels between 30 and 45 ugm/dl. Lead levels and scores on developmental tests will be measured pre-treatment, post-treatment and at 6 months from study enrollment. Results will be compared between the two groups regarding change in lead levels and developmental test scores.